1. Field of the Invention
This invention relates to high chroma polyolefin compositions stabilized by the incorporation of a hindered amine light stabilizer.
2. Discussion of the Related Art
Various exterior components of automotive vehicles can be made from lightweight durable plastic materials, such as thermoplastic polyolefin-based mixtures. The component can be painted, or can have colorants mixed or blended into the plastic mixture itself. A concern with painted components is the adhesion of the paint to the surface of the plastic component. While concerns about paint adhesion are not present with plastic mixtures that incorporate the colorants, there are concerns about the degradation and durability of the colorants due to exposure to environmental extremes in temperature, humidity, stress, and light, especially ultraviolet radiation.
It is known to incorporate UV absorbers or screeners, along with other light stabilizers into plastic mixtures. One category of known light stabilizer is the hindered amine light stabilizer (hereinafter “HALS”). Plastic mixtures must be carefully formulated in order to meet structural requirements, to meet weight requirements, to maintain color characteristics, to prevent “bloom” or haze from forming, to meet cost objectives, and to meet these various objectives over the lifetime of the product into which a component made from the plastic mixture is incorporated.
Many thermoplastic components utilized for automotive exterior applications are muted in color intensity, or chroma value. Black and gray bumpers, claddings, grilles, and skid garnishes are typical automotive exterior applications for low chroma thermoplastics.
Trends in automotive vehicle design utilize more intense color palettes for both exterior and interior components. A need exists for higher color saturation or chroma thermoplastic compositions which can meet rigorous physical and chemical demands for weatherability and color longevity required for the automotive applications.